title: Depletion of the adaptor protein NCK increases UV-induced p53 phosphorylation and promotes apoptosis.
abstract: The cellular response to DNA damage requires the coordination of many proteins involved in diverse molecular processes. Discrete molecular pathways are becoming increasingly well understood, but the interconnectivity and coordination of multiple pathways remains less clear. We now show that NCK, an adapter protein involved in cytoskeletal responses to tyrosine kinase receptor signaling, accumulates in the nucleus in response to DNA damage and this translocation can be blocked by specific inhibition of the ATR protein kinase. Strikingly, HeLa cells depleted of NCK undergo apoptosis shortly after UV irradiation, as monitored by caspase-3 cleavage and PARP cleavage. This rapid, hyperactive apoptosis in NCK depleted cells might be p53 dependent, because loss of NCK also increased UV-induced p53 phosphorylation. Importantly, depletion of SOCS7, which is necessary for NCK nuclear translocation, phenocopies NCK depletion, indicating the nuclear accumulation of NCK is responsible for these molecular events. There are two NCK isoforms that have mostly redundant functions, and although NCK2 appears to have a greater contribution, depletion of NCK1 or NCK2, led to increased p53 phosphorylation and early apoptosis after UV exposure. These data reveal a novel function for NCK in regulating p53 phosphorylation and apoptosis, and provide evidence for interconnectedness of growth factor signaling proteins and the DNA damage response.
authors.affiliation: Department of Microbiology, Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Errington
authors.forename: Ian G
authors.initials: IG
authors.lastname: Macara
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency*; D017209:Apoptosis / Q000235:genetics / Q000528:radiation effects*; D053148:Caspase 3 / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D009687:Nuclear Proteins / Q000172:deficiency; D015513:Oncogene Proteins / Q000172:deficiency*; D010766:Phosphorylation / Q000528:radiation effects; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D020033:Protein Isoforms / Q000172:deficiency; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050826:Suppressor of Cytokine Signaling Proteins / Q000172:deficiency; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C078332:Nck protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; C108775:SOCS7 protein, human; D050826:Suppressor of Cytokine Signaling Proteins; D016159:Tumor Suppressor Protein p53; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3